void main() {
  // People p = new People();   // 不写new也可以
  People p = People();   // 不写new也可以
  p.username = "O椰";
  p.age = "18";
  p.say();
  p.run();
}



/*****
 * 
 * 前端中定义类
 * export class People {
  username: string = ""
  constrcutor (name: string) {
    this.username = name
  }
  say () {}
  run () {}
}
 * ****/

// 声明一个类
 class People {
  String? username = "";
  String? age = "";
  say() {
    print("我是${username}");
  }
  run() {
    print("${username}在跑");
  }
}